Sadly the carnal abandon in her lyrics fails to translate as lustful hanky-spanky on the big screen.

The plot is handcuffed tightly to the book.

As a favour to her flu-riddled roommate Kate (Eloise Mumford), English Literature student Anastasia Steele (Dakota Johnson) interviews handsome billionaire Christian Grey (Jamie Dornan) for an article in the university newspaper.

Anastasia is intoxicated but Christian initially pushes her away.

“I’m not the man for you. You have to steer clear of me,” he whispers.

Irresistibly drawn to the businessman, Anastasia agrees to a date and Christian spirits her away to his red room festooned with S&M toys via a flight on his private helicopter.

As she takes her first ride on his chopper to the throb of Ellie Goulding’s chart-topping hit Love Me Like You Do, Taylor-Johnson’s film reduces to an orgy of product placements and glossy fantasies that wouldn’t look too shabby as TV commercials for luxury cars, designer fragrances or crumbly, flaky confectionery.

Only in Taylor-Johnson’s film, the beautiful heroine, who bites her lower lip as lazy shorthand for anticipatory sexual pleasure, wants to unwrap Dornan’s sculpted torso rather than a glistening slab of milk chocolate.

“I’m incapable of letting you go,” confides Christian as he introduces wide-eyed Anastasia to his secret world of domination and submission, which didn’t get UK censors hot under the collar, passing the film uncut.

Nor me.

I was more aroused by the immaculate shine on Christian’s piano than anything in his boudoir of bondage: a set designer must have spent hours buffing those ivories.

When Dornan and Johnson are fully clothed and enjoying comical scenes of flirtation, they kindle smouldering screen chemistry.

As soon as one of them disrobes, those embers are extinguished.

Kelly Marcel’s script fails to flesh out the protagonists: Christian remains an enigma and Dornan gamely keeps a straight face as he barks lines like, “If you were mine, you wouldn’t be able to sit down for a week.”

The usual sexual inequality about on-screen nudity applies.

While Johnson is depicted full frontal, Dornan’s johnson remains artfully hidden by his co-star’s creamy thighs or high thread-count bed sheets.

In an early scene, Ana’s roommate excitedly demands the lowdown on Christian and the heroine coolly responds that he was nice, courteous and clean.

That’s a fair summation of the film: two hours of polite, functional, beautifully shot foreplay that fails to locate the G-spot.